Absorption refrigerating apparatus



-1 4 K. NESSELMANN EIAL 2,221,551

ABSQRPTION REFRIGERATING APPARATUS I Filed Aug.- 17, 1938 2 Sheets-Sheet 1 Patented Nov. 12, 1940 UNITED STATES ABSORPTION narmosaarmo APPARATUS Kurt Nesselmann and Ernst Sprengel, Berlin- Siemensstadt, Germany, assignors to Patentbelchrinkter verwertungs-G'eselllchaft mit 'Haitung Hermes, Berlin, Germany, a cornotation of Germany Application August 17, 1938. Serial No. 225.292 Germany August 17, 1937 The present invention relates to absorption refrigerating apparatus of the continuous type in which the difference in pressure between the generator and condenser on the one hand and the evaporator and absorber on "the other hand is maintained by two throttles inserted in the' circult of the operating medium. "According to the invention the volume of the generator-in such an apparatus is chosen so much greater than the volume of the absorber, evaporatonsupply conduits and the like that even when the absorber, the evaporator and the supply conduits are completely filled up with liquid enough solution is still left in the'generator to prevent a dangerous rise in temperature of the heating surface. In this manner absorption refrigerating apparatus of the above-indicated character are fully protected against all dangers which may be due to the failure of valves and pumps; the latter 20. serving in such apparatus in most cases to supply the solution from thenbsorber to the generator. Even if, for instance,- the "pump for circulating ;the solution fails to operate ior any reason dangerous overheating of the*heating surface can- 28 not occur when" dimensioning the apparatus according to t he-invention, since care is taken to have always a sufliciently large amount of solu-.

tion in the absorber. When carrying the invention into practice a. return conduit is, for instance, '80 in communication with the condenser and through which returns always an amount or solution to the generator, after the absorber, the evaporator and the supply conduits are filled up completely, that undue pressures and an undue '85 temperature stress of the heating surface are prevented. Absorption refrigerating apparatus of the continuous type according to the invention are preferably employed in domestic refrigerators.

According to the invention the excess quantities of operating liquid which have not been converted into vapor return from the evaporator to the absorber through an ascending return pipe whose opening lies in the lower part of the evaporator and is designed in the ionnoi an overflow in such a manner that a given height of the refrigerant level is maintained within the evaporator. In this case the inlet for the liquid refrigerant and the outlet for the solution flowso ing into the absorber are preferably arranged at diiferent points lying as far apart as possible. By the use of the ascending tube the relatively weak solution may pass from the evaporator into the return pipe. In order to prevent the ascending pipe to act as a siphon the upper end thereof is connected above the liquid level to the evaporator chamber. I! a flow of the vaporous refrigerant takes place through the pressure compensation tube the operation of the apparatus is not impaired thereby, since this refrigerant has already produced refrigeration by its evaporation and also reaches the absorber together with the excess quantities oi operating liquid.

The liquid refrigerant coming from the condenser may be cooled'in the usual manner below the point of liquefaction by means ot a heat ex-' a conduit extending" substantially-throughout the v entire length of the absorber and having a plurality' of outlet openings arranged side by side. According to the invention transverse ribs are arranged in the absorber so as to result in zones of difierent concentrations and of diflerent temperatures. The concentrated solution is caused to ,circulatethrough a heat exchanger which brings this solution into heat exchange with the zones arranged in the absorber. In this manner I the heat exchange is more eifective owing to the greater dlflerence in temperature between the rich solution returning to the generator and the weak solution entering the absorber.

In the accompanying drawings is shown an embodiment of the invention in diagrammatic form, in which Fig. 1 represents adiegrammatic layout. of an absorption system of the continuous type embodying the present invention.

Fig. 2 represents semi-diagrammatically and in sectional elevation the embodiment of the invention in a domestic refrigerator, and

Pig. 3 represents in horiaontai section the or I Referring to Fig. l, the reirigerant is expelled 2. The vaporous refrigerant passes through a conduit 3 into a rectifier 4 and then into the aircooled condenser 6 through the water-separator 5 provided with cooling ribs. The liquefied refrig- 5 erant then passes from the condenser 6 into the evaporator 'II by way of a conduit I, heat ex: changer 8, a conduit 9 and a fixed throttle it,

of the refrigerant pass through the weak solution contained in the absorber. The absorber I3 is designed in the form of a horizontal cylindrical container. Inside the container are arranged vertical bafli'es I6 which are so dimensioned in height as to be short of the liquid level. In this manner zones of difl'erent concentrations and of different temperatures are obtained. The arrangement of the bai'iies shown has the advantage that these zones of diiferent temperatures of absorption are more accurately separated with respect to each other than would otherwise be possible. The heat liberated during the absorption is directly carried off to the atmosphere by cooling ribs I 'I. The rich solution is forced from the absorber back into the generator I by means of a liquid circulating pump I8. The pump draws oil the absorption liquid through a conduit I9 and forces it through a heat exchanger 40 2I by way of a conduit 28 extending through the absorber. The rich solution passes from heat part of the generator I through a conduit :28

and passes at first into the heat exchanger t2I 5 where it comes into heat exchange with the rich solution flowing from the absorber. The weak solution flows from the heat exchanger 2| through a conduit 24 to the absorber I8. At the 4 inlet is provided a valve 28 operated by a float 55 25. By this valve the liquid level in the absorberis maintained constant and the high pressure in the generator is throttled to low pressure prevailing in the absorber.

In order to remove from the evaporator lithe 6o absorption solution entrained into the latter a U-shaped conduit 21 whose left limb is immersed in the liquid contained in the evaporator II is provided. Through this tube flows the liquid collected in the evaporator into the heat exchanger 65 8 and then back to the lower part of the absorber through a conduit 28. -In thev heat exchanger 8 the hot liquid refrigerant coming from the condenser through the conduit I exchanges heat with the liquid discharged from the evaporator. This 0 special arrangement of the heat exchanger presents the following advantages. The evaporated refrigerant flows in a cold state into the absorber where it is heated, thus relieving the absorber insofar as the quantity of heat, to be carried off from the latter to the outside, is reduced by the absorber.

is so arranged in the absorber that the vapors amount of heat which serves to heat the incoming cold refrigerant to the end temperature of the A further advantage of the heat exchanger consists in that the relative large amounts of refrigerant which fiow in an unevaporated state'through the conduits 21, 28 into the absorber are evaporated by this heat exchanger. In this manner the condensate is cooled to such an extent below the temperature of condensation that when the condensate is throttled the losses are reduced by the pre-evaporation in the capillary tube III. I The upper part of the U-shaped tube 21 is provided with a pressure compensation tube 28. The particular arrangement of the U-shaped tube 21 has the advantage that only the relatively weak solution passes from the evaporator into the return pipe.

matically maintained in the evaporator. 7

To protectthe apparatus against undue increases in pressure which may occur if the liquid flowing from the condenser 6 into the evaporator II fills up the heat exchanger I and the conduit erator.

'0! the parts of the apparatus shown the generator I, the rectifier 4, the heat exchanger 8 and the heat exchanger 2| for the solution are heatinsulated as will be seen from Fig. 1. The volume of the'generator is chosen according to the invention so much greater than the total volume of the absorber and the evaporatorthat whenthe evaporator, absorber, auxiliary conduits etc. are

completely filled up there remains enough solution in thev generator to prevent dangerous pressures and a dangerous temperature stress of the heating surface. M to'the relative position of the individual vessels shown in Fig. 1 the following may be pointed out:

'lhe evaporator II must lie in the arrangement shown higher than the absorber in order to en-' sure a discharge of the excess quantities of unevaporated operating liquid. The condenser must be located higher than the generator whereas the generator'and condenser may be located at any height with respect to the evaporator and absorber. Instead of the float-operated valve 28 shown in Fig. 1 also a capillary tube may be employed. The use of a float at this point is desirable, sincein this case 010881118 is prevented. A capillary tube I. must be employed in the apparatus shown in Fig. 1 in the condensate conduit extending from the condenser 8 to the evaporator II, since otherwise starting of the apparatus would be dililcult and a discharge of the excess quantities of the unevaporated operating liquid is thus ensured.

Figs. 2 and 3 show the arrangement of the refrigerating apparatus schematically represented in Fig. l disposed in a domestic refrigerator, the same numerals of reference denoting the same parts in all views. Fig. 2 shows a side elevation of the refrigerator is with the parts of the apparatus arranged in part in the insulation and located outside the cooling chamber 38 and Fig. 3 shows a horizontal sectional view of a refrigerator broken away, in the cooling chamber 88 of which is arranged the evaporator II. The inner con.- duit of the heat exchanger 8 and the return can- The tube 21 is so designed that a given height of the refrigerant level is auto-' frigerant coming from the capillary tube passes through a conduit 3| (Fig. 3) into the left duit 20 for the weak solution arranged in the absorber are designed in the form of spiral-shaped conduits in order to attain a good heat exchange. The intake conduit and the discharge conduit of the solution pump l8 are combined to form a double conduit (i. e., one within the other) in the embodiment shown in Fig. 2. The liquid reend of the cylinder-shaped evaporator. The ascending branch of tube 21 is here arranged in a closed tank 33 to the lower end of which is connected the discharge conduit 32 whose opening lies at a point as far apart as possible from the inlet for thecondensate through conduit 3|, thus ensuring a discharge of only the relatively weak solution from the evaporator. In Fig. 3, 36 denotes the chamber for the reception of the parts of the refrigerating apparatus lyingoutside the Y cooling chamber, shown in Fig.2.

What is claimed is; i

1. An absorption refrigerating apparatus of the continuous type comprising a generator, a condenser, an evaporator, a horizontal absorber and conduits between these parts, a throttle between said condenser and said evaporator, a-secand throttle between said absorber and said generator, both throttles serving to maintain the diiference in pressure between generator and condenser on the one hand and evaporator and ab-' sorber on the other hand, the supply conduit from the evaporator to the absorber consisting of a tube provided with a plurality of inlet openings lying side by side and extending substantially throughout the length of the absorber and transverse bailles disposed between said inlet openings, said baiiies extending upwardly short of the solution level so as to create zones of different concentration and different temperature, the conduit conveying the concentrated solution from the absorber to the generator extending through the length of said absorber past said several zones 'to bring the latter into heat exchange with said conduit.

2.-An absorption refrigerating apparatus of the continuous type comprising a generator, a condenser, an evaporator, an absorber and conduits between these parts, a throttle between said condenser and said evaporator, a second throttle between said absorber and said generator, both throttles serving to maintain a given difference in pressure between the generator and condenser on the one hand and the evaporator and absorber on the other hand, the volume of said generator and the quantity of the absorption solution contained therein being sumciently in excess of the volume of the absorber, the evaporator'and the appertaining supply conduits, so that in case the absorber, the evaporator and the supply conduits should become completely filled with the absorption solution,'enough solution still remains ,in the generator to prevent a dangerous temperature rise of the heating surface. and an overflow conduit connected at one end to said generator and at the other end to the condenser discharge conduit at a level with respect to the generator which, after filling of, the absorber, the evaporator and their connecting conduits with liquid, permits suflicient operating medium to return to the generator to prevent increase in pressure therein and dangerous heating of it: heating surface.

3. An absorption refrigerating apparatus of the continuous type comprising a generator, a

condenser, an evaporator, an absorber and conduits between these parts, a throttle between said condenser and said. evaporator, a second throttle between said absorber and saidgenerator,.both

in pressure between the generator and condenser on the one hand and the evaporator and absorber throttles serving to maintain a given difference on the other hand, the volumeof said generator thereof to only drain thelleanest portion of the refrigerant from the evaporator, the highest point of said curved conduit being connected with the evaporator space above .the refrigerant level to maintain automatically a given overflpw level of the evaporator.

4. An absorption refrigerating apparatus of the continuous type comprising a generator, a condenser, an evaporator, an absorber and conduits between these parts, a throttle between said condenser and said evaporator, a second throttle between said absorber and said generator, both throttles serving to maintain a given difference in pressure between thegenerator and condenser on the one hand and the evaporator and absorber on the other hand, the volume of said generator and the quantity of the absorption solution contained therein being sufliciently in excess of the volume of the absorber, the evaporator and the appertaining supply conduits, so that in case the absorber, the evaporator and the supply con duits should become completely filled with'the absorption solution, enough solution still remains in, the generator to prevent a dangerous temperature rise of the heating surface, the conduit connecting said absorber with said evaporator extending with an inverted curve into said evaporator and terminating in the lower portion thereof to only drain'theleanest portion of the refrigerant from the evaporator, the highest with the evaporator space above the refrigerant level to maintain automatically a given overflow level of the evaporator, the conduit connecting said condenser with said evaporator terminating in the upper portion of the evaporator.

KURT NESSEIMANN. ERNST BPRENGEL.

point of said curved conduit being connected 

